A collaborative project will use single stranded synthetic DNA oligonucleotides which form triplex structures with targeted DNA regulatory regions (TFOs) to test the hypothesis that they may be used as gene-specific therapy for skin cell dysfunction. The skin is an ideal model for genetic manipulation because it can be readily evaluated and grown in vitro. Psoriasis and skin cancer will be targeted for selective manipulation. In the first project, synthetic oligonucleotide analogues will be designed to target the promoter domain of the epidermal growth factor receptor gene (EGF-R) and tested for their capacity to selectively repress EGF-R in the A431 epidermal carcinoma line which overexpressed EGF-R. Since psoriasis overexpresses EGF-R as well as TGF-alpha which binds to that receptor, we will then study the ability of oligonucleotides with in vitro effect, for their capacity to downregulate EGF-R in psoriatic lesions. In the second project, we will attempt to manipulate the expression of Glutathione-S-transferase pi, GST-pi, an enzyme which is overexpressed in melanoma and squamous cell carcinoma and which may contribute to multidrug resistance. TFOs will be tested for their capacity to selectively repress GST-pi first in melanoma lines and subsequently, in metastatic melanoma to skin implanted into nude mice. In both models, skin will be removed following application of the oligonucleotides and assayed for mRNA expression by dot hybridization, Northern blotting, and in situ hybridization. These studies may lead to the development of a new class of therapeutic agents and provide insight into the pathogenesis of psoriasis and drug resistance in cancer.